Zyxel MAX206M2 returns service domain as part of digest.

I have been setting up trixbox over the last couple of days. I've been using X-lite on my computers with much success. I decided to try to use my old Xohm wimax router (router was replaced by clearwire, so I figured I could use it for something else). I have the sip extension configured, and the configuration is as correct as I can get it on the old Xohm router. When I try to connect the router to trixbox, I get the following error.

[Mar 11 20:35:36] WARNING[2132] chan_sip.c: username mismatch, have , digest has
[Mar 11 20:35:36] NOTICE[2132] chan_sip.c: Registration from '' failed for 'xxx.xxx.xxx.xxx' - Username/auth name mismatch

My question is this: How can I create a user "204@asterisk.domain.name.deleted" so that when the Xohm router tries to authenticate it can? I can't create an extension with that name, because the extension must be generic. I tried setting the account code on the extension itself, but that didn't work either. There is no setup-*** script that will work as far as I know.

Anyone have any ideas?

Create a trunk and use teh from-internal context. It will act like an extension if the type=friend. The trunk config will let you enter the domain.